使水资源具有再生性的原因是自然界的 A.
径流 B.
水文循环 C.
蒸发 D.
降水

单项选择题A guest says “thank you” after you helped her with her bags. What would you respond? A、You’re welcome but I must be off. B、My please. I’m John. Please call the bell desk if you need anything else. C、No problem. Take it easy. D、Don’t mention it.

多项选择题煤矿安全生产标准化管理体系进一步强化双重预防工作机制，这里的双重就是指( ) 和( ) 。 A. 风险分级管控 B. 隐患排查治理